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[me following examples and suggestions should be seen &s indicative 
for the practical consequences. They may be easier studied and evaluated 
by applying the presented framework, Other examples can be found scattered 
in the text; the reader may classify them under the six headings presented, 
Instrumental 
Images 
Environmental: 
Personnel 
Training 
Teaching 
oe 
ego the subjective optimum magnification of a steréscope 
for good paperprints and for geological interpretation 
was found to be 3x to 4x for black and white prints, 
2.D0x:50 3x for colourprints, and 2.2x to 3x for false 
colour prints (one Operator on the Interpretoscope). 
Binoculars are used only about 10% of the time for civil 
photo-interpretationo 
Coloured prints seem to disappoint interpretors, once they 
start drawing and interpretinge For instance, stereo-depth- 
-perception probably is impaired, as was found by sketching 
the drainage pattern. 
False colour probably is also "false" for the eyes, and 
causes visual fatigue. Is it not possible to colour the 
various layers more modestly and "natural"? 
Colour and false colour depth-perception is better with the 
terrain shadows falling away from the observer than towards 
him, as it is with black and white printse 
Is it a general rule, or is it accidental and subjective? 
Photo-interpretors should be encouraged to talk with 
colleagues , to express in their own language what they see. 
Speed and ability vary within a group of photo-interpretors. 
Do not expect everybody being equally efficient or accurate; 
it is à subjective profession, 
When are new-comers tooold to learn photo-interpretation? 
Is there a test to measure ability of persons to pick up 
new skills, if they are over 35? See the letter in the 
New Scientist of 13 June 1968, p. 558 (welder-test). 
Should not training of photo-interpretation start with large 
scale photographs, possibly coloured, and work with small 
and controlled steps to smaller scales? 
Training in the naming of colours and perception of colours 
is probably necessary in future (females!). 
Interpretors should be made aware of optical illusions and 
other factors which falsify vision, e.ge "red is near", 
Is a kind of programmed learning with the help of teaching 
machines not feasible? A stereo sample-collection with audio 
input of the description (tape) and optical projection of 
indications in the stereo-image. Or oan it be realized 
with TV? 
  
Interpretation training with the double scanning stereoscope 
should preferably be carried out in separate cabins, such 
that teacher and pupil can talk aloud freely. The student 
should be strongly encouraged to draw the outlines and 
boundaries himself, as this stimulates learning too. 
(Vernon, Ch. 1)-]